I've seen a number of posts by people who wish to have a single program location shared by two operating systems on different partitions. I'm a bit curious about why anyone would do this since mass storage is so cheap these days. The little bit of space saved wouldn't seem to be adequate compensation for the operational issues that can arise from this arrangement.
Consider:
1. Many applications do not store ALL of their configuration data in the registry. Instead, they store some configuration information in the local program directory. Let's say you install an application of this type to a common location first to work with Win98SE on drive C:, then to work with W2K on drive D:. The local configuration information file(s) in the common location will be set to operate properly with W2K, NOT with Win98SE. In many cases there may not be a significant difference, or the differences present in configuration may relate to features of the software not used by the system owner. But the potential exists for serious operational ramifications. Interestingly enough, some of the worst scenarios of this sort occur with Microsoft Office apps.
2. What happens if you decide to uninstall the application? If you only wish to remove it from use in one of the operating systems, this should work out okay. You uninstall from the OS in which you no longer wish to use the application, then re-install in the OS in which you wish to keep using the application. But if you wish to remove the app from BOTH operating systems, you will have to uninstall in one OS, (re)install in the other OS, then uninstall in that same OS. It will work, I suppose, but it's pretty clumsy.
3. What happens if the app needs an upgrade of its executables or other "local" files for one OS but not for the other? This is a sort of reprise on the first item, but potentially much more serious, particularly in the case of a patched executable, a rather common situation with gaming software.
In the case of applications / utilities which are very simple, for instance utilities which don't even have an installation procedure (You just run them by double-clicking on the executable or by clicking on a shortcut to the executable.) none of this would pertain, of course. On the other hand, you wouldn't be saving much disk space by using a common installation location either.
Just thought I'd toss this $.02 into the pot. It may not be much of a contribution, but I thought it might be a good idea to mention it.
Regards,
Jim
Edit: danged spillchuck errors